The Efficacy of Continuous Bioaugmentation in Full-Scale Pulp and Paper Industry Aerated Stabilization Basins

Continuous bioaugmentation is widely employed across the pulp and paper industry toimprove resilience of wastewater treatment systems or performance in undersized (in terms ofvolume, aeration, or nutrient supply) systems. Theoretically, low concentrations of biomasscould be limiting the removal of a target substrate. However, bench and field scale researchinto bioaugmentation has shown that this straightforward relationship does not always play outas expected, and that success is often unpredictable. Bioaugmentation can be thought of asmicrobial immigration in ecological terms, and research has shown that immigrating microbialcommunities can play a large role in defining the microbial community structure of abioreactor, while other research into bioaugmentation failures have shown lack of survival ofthe bioaugmented organism to be a common reason for bioaugmentation failure.To elucidate the factors that lead to successful bioaugmentation, a critical review of theexisting literature was performed. The peer-reviewed literature was searched to develop adatabase of bioaugmentation application cases. These cases were analyzed via crisp-setqualitative comparative analysis (QCA) to identify pathways to success. A targetedbioaugmentation approach and the use of design characteristics such as immobilization werefactors that contributed to a successful bioaugmentation system. The QCA analysis alsodemonstrated that a measured change in alpha diversity is a good indicator for a successfulbioaugmentation application. Most of the studies included in the QCA were bench scale butapplying this type of analysis to full-scale studies would be more informative.For pulp and paper wastewaters, where bioaugmentation is a commonapproach to improving BOD and TSS removal, there is not a single full-scale study that has beenperformed with statistical analysis of permit driven metrics and microbial community analysis tounderstand the effect of bioaugmentation on plant performance and community assembly.A field scale trial at an existing aerated lagoon system treating pulp and paper mill wascompleted over a 6-month period. The system consisted of two nearly identical trains (Train 1and 2) of aerated stabilization basins (ASBs) operated by a pulp and paper company in thesoutheast United States. Each train consisted of two ponds in series, Ponds A and Ponds B. Thetrial was conducted in 2 phases. In the first phase, Train 1 was continually dosed with abioaugmentation product and Train 2 acted as a control (no treatment). In the second phase, thetreatments were switched; Train 2 was dosed with a bioaugmentation product and Train 1 actedas a control to eliminate train-specific biases and to have replication at the full-scale.Physical-chemical data were evaluated for differences between bioaugmented and controltrains with multiple linear regression, while controlling for the effects of environmental factorsand train. Throughout the trial, variation in sBOD5, TBOD5 or TSS at Ponds A was notassociated with the bioaugmentation factor. In Ponds B, the bioaugmentation factor wassignificant for SOUR, TBOD5 and TSS. T-tests indicated no significant difference in means ofdata collected for bioaugmented and control trains for SOUR and TBOD5, but that the Ponds BTSS average was about 6 mg/L higher in the bioaugmented trains compared to the control trains.While analysis of the physical chemical data suggests that bioaugmentation was a factor in BODand TSS of Ponds B, no evidence of higher biomass concentrations (from cATP data) or sBOD5 removal occurring in Ponds A was found. Further, analysis of 16S rRNA gene sequencingidentified high levels of Thiothrix in the bioaugmented Pond B, when TSS data between theponds diverged. This shows that the significant difference in TSS identified in PondsB could have been due to a microbial community dominated by a filamentous bacterial bloomrather than due to bioaugmentation.